Waddles and myself have managed to get our Pitchfork +1 without the need to go to all 6 zones with costumed NPCs.
Getting the Pitchfork +1
You and your partner need to be turned into *Goblins* and visit a certain balloon (e.g. in North Sandy it's the one at D-9) to get the Pitchfork +1.
There is, however, a *trick* to getting turned into a Goblin.
In North Sandy, the dark family of Trick monsters (Shadow, Shade, and Specter) gives you the costume of each nation's enemy beastman. However, if you trade a sweet to the one that gives the costume of *your* nation's beastman, you get turned into a Goblin.
This is the same for all nations, though the monster family might be different.
As a Hume Bastokan, I got turned into a Goblin by the Trick that normally turns people into Quadav. My partner (Waddles), a Windurstian Tarutaru, needed to trade to the Trick that turns people into Yagudo before he was able to be a Goblin.
We tested with the other shadow's each - nothing. So it's either race or (more likely) nation based.
It was a good puzzle though. We enjoyed getting the Pitchfork +1, even if it did take hours to work out :/